STABLE SIZE DISTRIBUTION IN A MATHEMATICAL MODEL FOR TUMOR CELL POPULATION GROWTH DURING CHEMOTHERAPEUTICAL TREATMENT WITH TWO NON-CROSS RESISTANT DRUGS
A size-structured model is developed to study the growth of tumor cell populations during chemotherapeutic treatment with two non-cross resistant drugs, [Formula: see text] and [Formula: see text]. The cells reproduce by fission. Four types of cells are considered: sensitive cells to both [Formula: see text] and [Formula: see text], cells that are resistant to [Formula: see text] only, cells that are resistant to [Formula: see text] only, and cells that are resistant to both [Formula: see text] and [Formula: see text]. Resistant cells arise by spontaneous genetic mutation from sensitive cells and are selected during the growth of the mixed population. The model consists on a system of linear partial differential equations describing the size-density of each type of cells. That corresponds to chemotherapeutic treatment on a given time sequence intervals such that, we continuously apply [Formula: see text] at a first interval and next we apply [Formula: see text] at a second interval, and so forth. We obtain a stable size-distribution theorem for this case.